Effects of carbon dioxide on different PSK modulation formats of Optical Wireless Communications using USRP

Abstract

This article explores the influence of the concentrated carbon dioxide (CO 2) gas on the different Phase Shift Keying (PSK) modulations used for Optical Wireless Communication (OWC) links. In this work, the OWC consisted of a laser diode, a photodetector, and a transmission medium. The Universal Software Radio Peripheral (USRP) unit created and evaluated the PSK modulations. This unit modulated the laser diode on the transmitter side and demodulated the data which were received by the photodetector on the receiver side. The CO 2 gas was emitted as a consequence of sublimation of the solid carbon dioxide in hot water. The measurements were done in a closed box in laboratory. The CO 2 gas is a one element of smog which pollutes cities now and then. Our experimental results with CO 2 gas could help to choose a suitable modulation scheme for OWC which are installed in cities with smog-polluted atmospheric conditions.